Joe Bastardi addressed this on his Saturday update. Basically their are 5 or 6 ways to calculate the temperatures. NOAA picks the one that produces the warmest results.
Just like measuring CO2 on the top of Mauna Loa, a volcanoes that emits all sorts of gasses including CO2.
Global[W]armists’ preferred method of determining the temperature is to stick up a moistened finger into the breeze created by TPTB thumbing through the Research cash ....